Layer the base by placing the chopped onions and cubed potatoes into the bottom of your slow cooker.
Add the sauerkraut over the potatoes, spreading it into an even, tangy blanket to trap the steam and moisture.
Whisk the liquid by mixing the apple juice and brown sugar, then pour it over the mixture to perfectly balance the acidity of the kraut.
Arrange the sausage pieces on top so their savory, smoky fats can drip down and season the potatoes as they cook.
Season the pot with caraway seeds and black pepper to enhance the rustic, heritage aroma of the dish.
Cover and cook on LOW for 6 to 7 hours (or HIGH for 3-4 hours) until the potatoes are perfectly fork-tender.
Stir gently just before serving to distribute the rich, concentrated juices and smoky bits throughout the pot.
Serve hot directly from the slow cooker for a soul-warming meal that hits all the right salty, tangy, and sweet notes.